The Perivascular Astroglial Sheath Provides a Complete Covering of the Brain Microvessels: An Electron Microscopic 3D Reconstruction
The Perivascular Astroglial Sheath Provides a Complete Covering of the Brain Microvessels: An Electron Microscopic 3D Reconstruction
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DOI：
10.1002/glia.20990
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发表时间：
2010-07-01
期刊：
影响因子：
6.2
通讯作者：
Ottersen, Ole Petter
中科院分区：
文献类型：
--
作者：
Mathiisen, Thomas Misje;Lehre, Knut Petter;Ottersen, Ole Petter
AQP4在血管周围星形细胞终末的极化分布的解体重新引起了人们对星形胶质细胞在控制脑-血界面的水和离子交换中的作用的兴趣。端脚的重要性是基于它们构成了对血管壁的完全覆盖这一前提。尽管基于不同的微观技术进行了一些研究，但这个问题尚未得到解决。我们在电子显微镜下对大鼠海马区CA1(分子层)血管周围终足进行了三维重建。末端脚趾交错重叠，中间不留缝隙。只有少数部位的突起--暂定为小胶质细胞突起--穿过血管周围的神经胶质鞘，与内皮基底板建立直接联系。与内皮细胞的内足覆盖不同，周细胞的内足覆盖是不完整的，允许神经细胞分子接触包裹这种类型细胞的基板。3D重建还显示了终足突起中的大量线粒体束，这些线粒体与血管周围的终足膜非常接近。我们的数据支持这一观点，即在病理生理条件下，血管周围星形细胞覆盖可能控制血液和脑之间的水和溶质的交换，而自由扩散仅限于重叠的终足之间的狭窄裂隙。(C)2010年Wiley-Liss公司
The unravelling of the polarized distribution of AQP4 in perivascular astrocytic endfeet has revitalized the interest in the role of astrocytes in controlling water and ion exchange at the brain-blood interface. The importance of the endfeet is based on the premise that they constitute a complete coverage of the vessel wall. Despite a number of studies based on different microscopic techniques this question has yet to be resolved. We have made an electron microscopic 3D reconstruction of perivascular endfeet in CA1 (stratum moleculare) of rat hippocampus. The endfeet inter-digitate and overlap, leaving no slits between them. Only in a few sites do processes-tentatively classified as processes of microglia-extend through the perivascular glial sheath to establish direct contact with the endothelial basal lamina. In contrast to the endfoot covering of the endothelial tube, the endfoot covering of the pericyte is incomplete, allowing neuropil elements to touch the basal lamina that enwraps this type of cell. The 3D reconstruction also revealed large bundles of mitochondria in the endfoot processes that came in close apposition to the perivascular endfoot membrane. Our data support the idea that in pathophysiological conditions, the perivascular astrocytic covering may control the exchange of water and solutes between blood and brain and that free diffusion is limited to narrow clefts between overlapping endfeet. (C) 2010 Wiley-Liss, Inc.